The present invention aims at improving the robustness of the systems of an aircraft, in particular a transport airplane, and including the ADIRS (Air Data Inertial Reference System) type air data and inertial data system, which, as known, represents an inertial reference station integrating the functions of the anemobarometric station. Such an air data and inertial data system being on board the aircraft usually provides, in real time, in particular a TAS (True Air Speed) type air speed and a conventional CAS (Calibrated Air Speed) type speed. Such a measurement system comprises, to this end, in particular, specifically total pressure probes (Pitot tubes).
Now, when such pressure probes are obstructed or frozen, it could lead to a loss of air data, and including to an alteration of the flight control primary functions. In particular, this could lead to excursions beyond the limit speeds, resulting in adverse effects on the stability of the aircraft. Erroneous or absent air data could, for example, occur upon breakdowns of systems, erroneous information of sensors, or upon the presence of frost or ice crystals.
It is known that frost is a meteorological phenomenon, the occurrence conditions of which are related to humidity and to static temperature. In the presence of frost, an accretion phenomenon can occur on the leading edges of the wings, of the stabilizer and of the rudder, as well as on all bumps. Frost can also have effects on sensors, such as total pressure probes, as far as leading to the measurement being altered, making it sometimes erroneous (frozen or biased).
It is thus necessary to be able to detect an error in the measurements performed by an air data and inertial data system, in particular an error in the speed provided by such a system.
Generally, aircrafts comprise systems comparing between them the information provided by different sensors. Thus, if most of the sensors provide a similar value, such a value could be considered as true. However, in some cases, being actually very rare, such sensors could be, either all or most of them, submitted to a similar frost phenomenon, so that the systems of the aircraft and the pilots can be without any reliable indication about speed or be unable to eliminate the erroneous speed(s).